Cycloid transmission with chain link ring

ABSTRACT

Examples are provided that describe a cycloid transmission with a chain link ring. An example cycloid transmission includes a motor shaft attached to a disc. The motor shaft may be used for rotating the disc. The cycloid transmission also comprises an outer chain link ring that surrounds the disc. The outer chain link ring includes rollers that are inserted at given interfaces between links of the outer chain link ring. The rollers contact the disc as the disc rotates. The cycloid transmission also comprises a housing. The links of the outer chain link are coupled at the given interfaces. The rollers are inserted at the given interfaces and into the housing.

CROSS REFERENCE TO RELATED APPLICATION

The present disclosure is a continuation of U.S. patent application Ser.No. 14/292,967, filed on Jun. 2, 2014, the entire disclosure of which isherein incorporated by reference.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Use of electric motor actuators in a wide array of engineering designcan be attributed to the ease of introducing motion and the need forpreventing motion as required by a mechanism or system. An ability ofactuators to enable control without use of oil has also made actuators apopular choice in various implementations. Electric motor actuators forrobotic and automation systems often require a transmission (speedreducer) in order to operate within speed-torque requirements of aspecific application and of the motor.

As an example, an electric linear actuator may exhibit a high speed andfast response that is useful when high acceleration and an ability tobrake quickly are needed. However, linear actuators tend to have a highcost, require a cooling option based on heat generated, and are limitedby a length associated with a given application. As another example, astepper motor has a capability to be highly reliable but withdiminishing torque as a speed of the motor is increased. There continuesto be a vast majority of robotic and automation systems being developedwith the aid of electric motors that are capable of performing arotational motion.

SUMMARY

In one example, a cycloid transmission is provided that comprises amotor shaft that is attached to a disc. The motor shaft is used forrotating the disc. An outer chain link ring surrounds the disc. Theouter chain link ring includes rollers that are inserted at giveninterfaces between links of the outer chain link ring. The rollerscontact the disc as the disc rotates. The cycloid transmission alsocomprises a housing. The links of the outer chain link are coupled atthe given interfaces. The rollers are inserted at the given interfacesand into the housing.

In another example, a cycloid transmission is provided that comprises adisc. The disc includes a surface along an outside perimeter. The discis surrounded by a chain link ring. The chain link ring includes aplurality of outer links and a plurality of inner links. A plurality ofrollers are inserted at given interfaces between the plurality of innerlinks of the chain link ring. The plurality of rollers contact the discas the disc rotates. The cycloid transmission also comprises a pluralityof pins that connect the plurality of outer links and the plurality ofinner links. The chain link ring is supported by a housing. The housingcomprises a plurality of slots for receiving respective pins of theplurality of pins. The plurality of slots also allows for a relativeposition of the chain link ring to the disc to be adjusted.

In another example, a cycloid transmission is provided that comprises adisc and a shaft for rotating the disc. The disc includes a plurality ofcircular openings. The cycloid transmission also comprises a cage gear.The cage gear comprises a top ring that is coupled to a bottom ring by aplurality of pins. A plurality of rollers covering the plurality of pinsand positioned between the top ring and the bottom ring. The pluralityof rollers contact the disc as the disc rotates. The cycloidtransmission also comprises a housing for supporting the cage gear. Thehousing comprises a plurality of slots for receiving the plurality ofpins.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates an exploded view of an example cycloid transmission.

FIGS. 1B-1D illustrate a portion of various examples of a chain linkring.

FIG. 2A illustrates an exploded view of another example cycloidtransmission.

FIG. 2B illustrates a top view of another example cycloid transmission.

FIG. 2C illustrates exploded view of a portion of an example chain linkring.

FIG. 2D illustrates a portion of another example chain link ring.

FIG. 2E illustrates a cross-sectional view of an example channel.

FIG. 3A illustrates an exploded view of another example cycloidtransmission.

FIGS. 3B-3C illustrate bottom and side views of an example cage gear.

FIG. 3D illustrates a side view of another example cage gear.

FIG. 3E illustrates another side view of another example cage gear.

FIG. 4 illustrates an example robotic system.

DETAILED DESCRIPTION

The following detailed description describes various features andfunctions of the disclosed systems and methods with reference to theaccompanying figures. In the figures, similar symbols identify similarcomponents, unless context dictates otherwise. The illustrative systemand method embodiments described herein are not meant to be limiting. Itmay be readily understood that certain aspects of the disclosed systemsand methods can be arranged and combined in a wide variety of differentconfigurations, all of which are contemplated herein.

Examples described herein include subsystems that enable a robotic endeffector, including a cycloid transmission, to operate in a rotationalmanner for an extended period of time. The cycloid transmission mayinclude a motor shaft that is attached to a disc. The motor shaft may beused to rotate the disc around an outer chain link ring that surroundsthe disc. The outer chain link ring may include rollers that may beinserted at given interfaces between links of the outer chain link ring.The rollers may serve to contact the disc as the disc rotates. Thecycloid transmission may include a housing wherein the links of theouter chain link ring are coupled at the given interfaces. The rollersare inserted at the given interfaces and into the housing.

Referring now to the figures, FIG. 1A illustrates an exploded view of anexample cycloid transmission 100. The cycloid transmission 100 comprisesa motor shaft 102 coupled to a bushing 103. The bushing 103 may bepositioned between the motor shaft 102 and a disc 104 as is illustratedin FIG. 1A. The motor shaft 102 may be used to rotate the disc 104. Thecycloid transmission 100 comprises an outer chain link ring 106 thatsurrounds the disc 104 as is illustrated in FIG. 1A.

The disc 104 may also comprise a plurality of teeth 105 along an outeredge 107 of the disc 104. The plurality of teeth 105 may interface withthe outer chain link ring 106. The plurality of teeth 105 may beadjusted to any given number based on the desired speed reductionassociated with the cycloid transmission 100. The outer chain link ring106 may also be adjusted in order to accommodate any adjustments made tothe plurality of teeth 105 of the disc 104.

Within the cycloid transmission 100, the outer chain link ring 106 mayinclude rollers 108 inserted at given interfaces 110 and 112 betweenlinks 114 and 116 of the outer chain link ring 106. The rollers 108 willminimize a friction associated with the rollers 108 and the disc 104 asthe rollers 108 and the disc 104 come into contact. A minimization infriction between the rollers 108 and the disc 104 may result in a longerlife span of the outer chain link 106 and the disc 104 due to less wearassociated with the rollers 108 and the disc 104.

The cycloid transmission 100 may also include a housing 118 as is shownin FIG. 1A. The links 114 and 116 of the outer chain link ring 106 maybe coupled at the given interfaces 110 and 112. The rollers 108 may beinserted at the given interfaces 110 and 112 and at least some of therollers 108 may be inserted into the housing 118.

FIGS. 1B-1D illustrate a few different examples associated with theouter chain link ring 106.

In FIG. 1B, a portion of the outer chain link ring 106 is shown. In oneexample, the outer chain link ring 106 may comprise insertion of therollers 108 at every other interface 112 between links 114 and 116 ofthe outer chain link ring 106 as is shown in FIG. 1B.

In FIG. 1C, a portion of the outer chain link ring 106 is shown. In oneexample, the outer chain link ring 106 may comprise insertion of therollers 108 at the given interfaces 109 and 113 between links 114 and116 of the outer chain link ring 106 based on a pattern other thaninsertion into every interface as is shown in FIG. 1C.

In one example, the outer chain link ring may comprise the use of arubber seal such as a rubber o-ring or a rubber x-ring. The use of therubber seal can assist with vibration damping and also lessen the needfor lubrication. An internal lubrication of the outer chain link ringmay be kept in place by the use of the rubber seal. The rubber sealcould also help to extend the life of the outer chain link ring bypreventing contaminants from entering various places of the outer chainlink ring. A properly lubricated outer chain link ring will require lessservicing and thereby lower the cost of maintenance associated with thecycloid transmission.

In one example, the outer chain link ring may comprise a double rowchain link ring. The double row chain link ring would enable a seconddisc to be used in the cycloid transmission. The second disc could bephased at 180 degrees from the disc in order reduce vibration andprovide a smaller bearing size. It is also possible to use a triple rowchain link ring with a third disc in addition to the disc and the seconddisc.

In FIG. 1D, a portion of the outer chain link ring 106 is shown. In oneexample, the outer chain link ring 106 may comprise insertion of therollers 108 at every interface 112 between links 114 and 116 of theouter chain link ring 106 as is shown in FIG. 1D.

By adjusting a number of the rollers 108 that are used in the outerchain link ring 106, it may be possible for various configurations ofthe disc 104 to be implemented within an example cycloid transmission.This may permit a reduction ratio to be achieved based on the specificrequirements of the cycloid transmission.

FIGS. 2A and 2B illustrate two views of an example cycloid transmission200.

FIG. 2A illustrates an exploded view of an example cycloid transmission200. The cycloid transmission 200 comprises a disc 202 surrounded by achain link ring 206. As is shown in FIG. 2A, the cycloid transmission200 includes a housing 208 for supporting the chain link ring 206.

The disc 202 includes a surface 203 along an outside perimeter 204. Thesurface 203 makes contact with the chain link ring 204 as the disc 202rotates.

The chain link ring 206 includes a plurality of outer links 210 and aplurality of inner links 212. As is shown in FIG. 2A, a plurality ofrollers 214 are inserted at given interfaces 216 and 217 between theplurality of inner links 212 of the chain link ring 206. The pluralityof rollers 214 contact the disc 202 as the disc 202 rotates. The chainlink ring 206 includes a plurality of pins 218 that connect theplurality of outer links 210 and the plurality of inner links 212.

Referring to FIG. 2A, the housing 208 comprises a plurality of slots 209for receiving respective pins of the plurality of pins 218.

In one example, a given pin from the plurality of pins 218 is insertedat every other slot of the plurality of slots 209.

In one example as shown in FIG. 2A, the plurality of outer links 210 arecoupled at the given interfaces 216 and 217. Respective pins from theplurality of pins 218 are inserted through the given interfaces 216 and217 and into the housing 208.

In one example after a given period of time, the plurality of rollers214 may no longer contact the surface 203 of the disc 202 as required bythe cycloid transmission 200 due to a wearing away of the surface 203 ofthe disc 202. Adjustment of a relative position of the chain link ring206 to the disc 202 may allow for an improvement in operation byensuring that a close contact between the surface 203 of the disc 202and the plurality of rollers 214 continues to occur.

FIG. 2B illustrates a top view of the cycloid transmission 200.Referring to FIG. 2B, the plurality of slots 209 allow for the relativeposition of the chain link ring 206 to the disc 202 to be adjusted basedon positioning of the chain link ring 206 in the housing 208 and aselection of which slots 209 to utilize.

In one example, the plurality of slots 209 are configured in a circularpattern within the housing 208 as is shown in FIG. 2B.

Referring to FIG. 2C, an exploded view of a portion of the outer chainlink ring 206 is shown. The outer chain link ring 206 may include theplurality of outer links 210 that are coupled to the plurality of innerlinks 212 by the plurality of pins 218.

In one example, the plurality of pins 218 are surrounded by a pluralityof bushings 219. The plurality of bushings 219 are surrounded by theplurality of rollers 214. The plurality of bushings 219 allow for theplurality of rollers 214 to move freely around the plurality of bushings219 as the plurality of rollers 214 may contact with the disc 202. Theplurality of bushings 219 may reduce a friction associated with theplurality of rollers 214 and the disc 202 as the plurality of rollers214 and the disc 202 come into contact. A reduction in the friction mayincrease the life span of the cycloid transmission 200.

Referring to FIG. 2D, a portion of the outer chain link ring 206 isshown. Referring to FIG. 2D, the plurality of pins 218 protrudes fromthe plurality of outer links 210.

FIG. 2E illustrates a cross-sectional view of a portion of the housing208. In one example, the housing 208 comprises a channel 211 to receivethe chain link ring 206 as is shown in FIG. 2E. The channel 211 mayinclude the plurality of slots 209. The plurality of pins 218 may bepositioned within the plurality of slots 209.

As the disc 202 rotates around the outer chain link ring 206, a radialforce from the disc 202 towards the outer chain link ring 206 may form.This radial force may cause the plurality of outer links 210 and theplurality of inner links 212 to make contact with a given internal sideof the housing 208. Due to a cavity associated within the channel 211,the channel 211 may allow a certain degree of a movement of the outerchain link ring 206 that is away from the disc 202 without the chainlink ring 206 making contact with any internal side of the housing 208.Removing any contact between the chain link ring 206 and the housing 208based on the radial force from the disc 202, may serve to extend thelife of the chain link ring 206.

In one example, the channel 211 may include a plurality of slots 209that are located on a top 220 and a bottom 222 of the channel 211 as isshown in FIG. 2E. This may allow for a given pin of the plurality ofpins 218 to be positioned at a given slot of the plurality of slots 209.As is shown in FIG. 2E, the plurality of pins 218 may be held in on thetop and the bottom of the channel.

In one example, the top 220 of the channel 211 is removable in order toprovide access to the chain link ring 206. The top 220 of the channel211 may be coupled to the bottom 222 of the channel 211 by a fastener224 as is shown in FIG. 2E. Enabling the top 220 of the channel 211 tobe removed would permit the chain link ring 206 to be replaced orserviced in order to increase an ease of service associated with thecycloid transmission 200. The capability to replace or service the chainlink ring 206 may also help to reduce a need for a tight toleranceassociated with manufacturing of the housing.

FIG. 3A illustrates an exploded view of another example cycloidtransmission 300.

Referring to FIG. 3A, the cycloid transmission 300 comprises a shaft 302for rotating a disc 404. The cycloid transmission 300 comprises a cagegear 306 and a housing 308 for supporting the cage gear 306 as is shownin FIG. 3A.

Referring to FIG. 3A, a plurality of rollers 309 contact the disc 404 asthe disc 404 rotates.

In one example, the disc may include a plurality of circular openings303 as is shown in FIG. 3A.

Referring to FIG. 3A, in one example the cycloid transmission 300comprises a plurality of output shaft rollers 305. The plurality ofoutput shaft rollers 305 are inserted through the plurality of circularopenings 303 in order to stabilize a motion of the disc 404 as the disc404 rotates.

FIGS. 3B and 3C provide two different views of the cage gear 306.

Referring to FIG. 3B, a bottom view of the cage gear 306 is shown. Aplurality of pins 307 coupled to a bottom ring 312 is shown in FIG. 3B.

Referring to FIG. 3C, a side view of the cage gear 306 is shown. A topring 310 is coupled to the bottom ring 312 by the plurality of pins 307.The plurality of rollers 309 are positioned over the plurality of pins307 and between the top ring 310 and the bottom ring 312 as is shown inFIG. 3C.

In one example, the cage gear 306 includes a first annular body coupledto a second annular body by the plurality of pins 307 as is shown inFIG. 3C.

In one example, a plurality of bushings 314 may be positioned betweenthe plurality of pins 307 and the plurality of rollers 309 as is shownin FIG. 3C. Positioning the plurality of bushings 314 between theplurality of pins 307 and the plurality of rollers 309 may minimize afriction between the plurality of pins 307 and the plurality of rollers309 as the plurality of rollers 309 contact the disc 404.

Referring to FIG. 3C, in one example the plurality of pins 307 protrudesfrom the bottom ring 312. This may allow for the cage gear 306 to besecured into the housing 308.

FIGS. 3D and 3E illustrate various examples of the cage gear 306.

Referring to FIG. 3D, in one example the plurality of pins 307 protrudesat every other location associated with the plurality of rollers 309.

Referring to FIG. 3E, in one example the plurality of pins 307 protrudesfrom the top ring 310 and the bottom ring 312.

FIG. 4 shows an example robotic system 400 where a cycloid transmission402 may be implemented in order to assist with a rotational movement.The robotic system includes an end effector 406 that is used to interactwithin an environment.

A latch 404 permits access to the cycloid transmission 402 as is shownin FIG. 4. The ability to access the cycloid transmission 402 by use ofthe latch 404 will permit an outer chain link ring of the cycloidtransmission 402 to be adjusted or replaced.

The outer chain link ring of the cycloid transmission 402 may bereplaced when the robotic system starts to exhibit an unintendedoperation associated with a movement of the end effector 406. In oneexample, the outer chain link ring may be replaced with a second outerchain link ring. This may allow for the inspection of the outer chainlink ring to ensure a proper amount of tension exists within the outerchain link ring. The ability to remove the outer chain link ring throughthe latch 404 may also permit the application of any necessarylubrication associated with the outer chain link ring.

Maintaining the outer chain link ring in an optimal state may permit thecycloid transmission 402 to operate in an effective manner and therebyallow for an intended operation of the robotic system 400.

It should be understood that arrangements described herein are forpurposes of example only. As such, those skilled in the art willappreciate that other arrangements and other elements (e.g. machines,interfaces, functions, orders, and groupings of functions, etc.) can beused instead, and some elements may be omitted altogether according tothe desired results. Further, many of the elements that are describedare functional entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location, or other structural elementsdescribed as independent structures may be combined.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims, along with the full scope ofequivalents to which such claims are entitled. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting.

What is claimed is:
 1. A cycloid transmission comprising: a disc,wherein the disc includes a plurality of circular openings; a shaft forrotating the disc; a cage gear comprising: a plurality of pins; a topring that is coupled to a bottom ring by the plurality of pins; aplurality of rollers covering the plurality of pins and positionedbetween the top ring and the bottom ring, wherein the plurality ofrollers contact the disc as the disc rotates; and a housing forsupporting the cage gear, wherein the housing comprises a plurality ofslots for receiving the plurality of pins.
 2. The cycloid transmissionof claim 1, further comprising a plurality of output shaft rollers,wherein the plurality of output shaft rollers are inserted through theplurality of circular openings in order to stabilize a motion of thedisc as the disc rotates.
 3. The cycloid transmission of claim 1,further comprising a plurality of bushings that are positioned betweenthe plurality of pins and the plurality of rollers for reducing afriction between the plurality of pins and the plurality of rollers asthe plurality of rollers contact the disc.
 4. The cycloid transmissionof claim 1, wherein the plurality of pins protrudes from the bottomring.
 5. The cycloid transmission of claim 4, wherein the plurality ofpins are inserted into the plurality of slots of the housing to securethe cage gear into the housing.
 6. The cycloid transmission of claim 4,wherein the plurality of pins protrudes at every other locationassociated with the plurality of rollers.
 7. The cycloid transmission ofclaim 1, wherein the plurality of pins protrudes from the top ring andthe bottom ring.
 8. The cycloid transmission of claim 1, wherein thedisc comprises an outer edge and a plurality of teeth along the outeredge for interfacing with the cage gear.
 9. A cycloid transmissioncomprising: a shaft for rotating a disc; a cage gear comprising: aplurality of pins; a top ring that is coupled to a bottom ring by theplurality of pins; a plurality of rollers covering the plurality of pinsand positioned between the top ring and the bottom ring, wherein theplurality of rollers contact the disc as the disc rotates; and a housingfor supporting the cage gear, wherein the housing comprises a pluralityof slots for receiving the plurality of pins.
 10. The cycloidtransmission of claim 9, further comprising: the disc, wherein the discincludes a plurality of circular openings; and a plurality of outputshaft rollers, wherein the plurality of output shaft rollers areinserted through the plurality of circular openings in order tostabilize a motion of the disc as the disc rotates, wherein the disc,the plurality of output shaft rollers, and the cage gear are insertedinto the housing.
 11. The cycloid transmission of claim 10, wherein thedisc comprises an outer edge and a plurality of teeth along the outeredge for interfacing with the cage gear.
 12. The cycloid transmission ofclaim 9, further comprising a plurality of bushings that are positionedbetween the plurality of pins and the plurality of rollers for reducinga friction between the plurality of pins and the plurality of rollers asthe plurality of rollers contact the disc.
 13. The cycloid transmissionof claim 9, wherein the plurality of pins protrudes from the bottomring.
 14. The cycloid transmission of claim 13, wherein the plurality ofpins are inserted into the plurality of slots of the housing to securethe cage gear into the housing.
 15. The cycloid transmission of claim13, wherein the plurality of pins protrudes at every other locationassociated with the plurality of rollers.
 16. A cycloid transmissioncomprising: a disc, wherein the disc includes a plurality of circularopenings; a shaft for rotating the disc; a cage gear into which the discis positioned, the cage gear comprising: a plurality of pins; a top ringthat is coupled to a bottom ring by the plurality of pins; a pluralityof rollers covering the plurality of pins and positioned between the topring and the bottom ring, wherein the plurality of rollers contact thedisc as the disc rotates; a plurality of output shaft rollers, whereinthe plurality of output shaft rollers are inserted through the pluralityof circular openings of the disc to stabilize a motion of the disc asthe disc rotates within the cage gear; and a housing for supporting thedisc, the plurality of output shaft rollers, and the cage gear, whereinthe housing comprises a plurality of slots for receiving the pluralityof pins to secure the cage gear into the housing.
 17. The cycloidtransmission of claim 16, further comprising a plurality of bushingsthat are positioned between the plurality of pins and the plurality ofrollers for reducing a friction between the plurality of pins and theplurality of rollers as the plurality of rollers contact the disc. 18.The cycloid transmission of claim 16, wherein the plurality of pinsprotrudes from the bottom ring.